Compressor



Aug. 1l, 1953 E. A. STALKER COMPRESSOR 2 Sheets-Sheet 2 Filed O01.. 23, 1945 Flag 9 INVENTOR.

* imiimif" Patented Aug. 11,

UNITED smrss PAT'- 'lf' OFFCE This invention relates to compressors, in particular to a new type compressor uniquelyv uti lizing a principle herein calledsupersonic ram'diffusion which will be discussed in the following description and explanation of the accompanying drawings.

It is an object of this inventionto provide""'a compact and efficient compressorV of'light weight, small dimensions and low cost. K

Another object is to provide an efficient means of reducing windage losses.

Another object is to provide an efficient supersonic compressor.

Other objects will appear from the following description, the accompanying drawings,` andthe appended claims.

I accomplish the above objects by theV means illustrated in the accompanying drawings'v in which- Figure 1 is a sectional View of the compressor taken normal to a vertical plane through the rotor axis.

Figure la is a cross section of a typical streamlined hub support vane at the entranceto the compressor taken along line la-la of Figure 1.

Fig. 1b is a partial sectional view on the same plane as Fig. l showing an alternative slot arrangement.

Figure 2 is an enlarged fragmentary developed View of the compressor vanes looking inboard normal to a plane represented by line 2-2 of Figure 1.

Figure 3 is a section of the supersonic ram'diffusers taken along line 3-3 of Figure 2.

Figure 3a is a section of an alternate form'of the supersonic ram diffuser taken along line 3-3 in Figure 2. I

Figure 4 is a radial section of the stator dif-r fusers which follow the supersonic ram diffusers and is taken along line 4 4 of Figure 2.

Figure 5 is a quarter segment'front'v View ofv the centrifugal impeller with its shroudremov'ed.

Figure 6 is a fragmentary side view partlyin section of another form of the invention.

Figure 7 is a fragmentary axial section'of lstill another form of the invention.

Figures 8 and 9 are vector diagrams showing respectively the conditions which exist when the flow of fluid is directed axially toward the rotor, and when it is directed at an angle theretoby means of the nozzle structure ahead of the rotor;

Cross reference is made to Prime Movers in Serial Number 593,631, filed May 14, 1945. i

This application differs from theapplication Serial No. 593,631 in that it deals withrotor passages having throats and with supersonic relative fluid velocities of the passage inlets. It is also concerned with counterrotating impellers and specific types of impellers which discharge fluid into the supersonic rotor.

Although this compressor could be designed to pump any compressible fluid, for simplicity of 2 explanation, it is assumed in the following discussion thatV the compressor is handling air.

The compressing of the air is accomplished by a' centrifugal impeller which discharges air substantially axially with respect to the impeller and into a counterrotating rotor having passages near its perimeter. The relative air velocity at the inlet of said passages is supersonic and the passages rst converge to reduce the velocity to sonic and th'en'diverge, thereby converting a large portion of the dynamic pressure to static pressure. The air leaving these supersonic ram diffuser passages discharges into stationary diverging passageswhere a large portion of the remaining velocity pressure is'converted to static pressure. 'Ihis'high pressure air is then discharged into a suitable collector for final delivery to the reservoir or machine forv which the compressor is employed.l

The compressor unit as shown in Figure 1 is housed in an outer case l made up of three coaxial sections la, lb and lc, housing the internal rotating and static elements.

The hub element 3, attached to housing la (see Figures 1 and 1a) by means of the radial streamlined Vanes 5, rigidly supports the stationary shaft 'l by means of key 9 and nut i l, which shaft in turn' mounts ball-bearings i3 and l5 of centrifugal impeller ll; ball-bearing i9 of the supersonic rain diffuser rotor 2l g and planet gears 23 by means of mounting bolts 25, hardened steel sleeve spacers 2l, and oil slinger reservoir 29, the purpose of which will be discussed in the subsequent description of the oil system.

The compressor power input shaft fil, which is supported by means of bearing 32, housing assembly 33 and support spokes ifl, from case ic, is brazed integral to rotor 2l to which is attached internal gear 35 of the impeller planetary gear systemby means of screws 3l. The action of internal gear ii'on planet gears 2S causes the sun gear 3S; which is attached to the centrifugal iinpeller I'l by means of screws 4l, to rotate impeller llin a counter direction to rotor 2l.

Figure 5 shows a quarter segment front View of impeller' il which is comprised of a plurality of 'radial'walls or vanes i3 disposed uniformly about the axis'of rotation. Air enters the centrifugal impeller rotor il making an angle of approximately 30 relative to the entrance plane at theV outside and approximately 19 relative tothe Ventrance plane at the inside. In order to reduce entrance losses to a minimum, Athe longer centrifugal impeller vanes ./ia should ac commodate the above angles relative to the entrance plane and spiral rearward, as shown in Figure` 5, toward radial axial planes at the exit suchthat 'when the air makes the accelerating turnl 45 at the exit as shown in Figure l, it will leave substantially axially with respect to the centrifugal impeller il, as shown in Figure 2. These vanesdS could be routed vfrom a solid rotor 3 blank by means of a router pivoted at radius R, Figure 1, said router actuating a cam-follower mechanism which automatically rotates the impeller blank to the correct azimuth of cut as the router progresses through its router arc R.

It will be noted in Figure 5 that three different vane lengths are indicated in the grouped relationship 43a., 13b and 43e, such that any particular blade is identical to the 3rd, 6th, 9th, etc. blades from itself. Blades 43a are full length, blades 43h are medium length, and blades 43e are short. For ease in fabrication, the shorter blades 43h and 43C are identical to like geometrical portions of full length blades 43a. The medium length blade 43h should be the next blade adjacent to the inside radius of the helical turn formed by the full length blades 43a, and the short blade 43C should be the next blade adjacent to the outside radius of this turn. Such a disposition of blades can be made to give the air a very even axial Velocity distribution about the exit circumference o impeller Il, and insures better compressor eiciency.

It will be noted in Figure 1 that a thin bellshaped shroud 47, which rotates with impeller Il, encloses impeller vanes 43 so as to form air-how passages 49. These passages are radially designed so as to gently diruse the high velocity entering air to a low relative duct velocity before making the turn 45. in turn 45 insures a constant axial velocity along a radial line at the impeller exit, which is another factor giving improved compressor eiilciency.

For an efficient compressor pumping air against a head of 80 pounds per square inch gauge, the velocity of eiilux of the jet from the impeller exist would be of the order of 800 feet per second, and when combined vectorially with the peripheral velocity the impeller exit, it would give an absolute leaving velocity of some 1450 feet per second. Under these conditions there would be a static pressure ratio o 1.4 at the exit from impeller Il.

. With the periphery of rotor 2| turning at a velocity of 900 feet per second in the opposite direction to impeller l1, the relative entering velocity of the air to the passages 5i formed by the supersonic ram diffuser vanes 53 on this periphery, is some 2250 feet per second found as the vector sum of 900 and 1450 feet per second. Figure 3 is a radial section of the supersonic ram difiusers taken along line 3 3 of Figure 2. Because the air velocity relative to the inlet at A is well above the velocity of sound, the rotor passages are convergent from A to B to bring the air to the velocity of sound at throat B of the passage 5l and then divergent to C in a normal diffusion passage. Due to centrifugal effects in the rotor passages 5| and also for easier fabrication, the inside surface 55 of the passage 5l, which is the outer surface of rotor 2l, can be a cylindrically turned surface into which oblique slots have been cut at regular intervals for insertion of vanes 53. These vanes and outer labyrinth ring 53 can be a brazed assembly with the rotor 2l and drive shaft 3l.

It will be noted in Figure 3 that boundary layer bleed-off ports 59 have been provided downstream rom throat B of passage 5I. These insure proper diffusion following the throat at design conditions and help to reduce the ill effects of shock burble at off design conditions.

It is important to control the boundary layer The acceleration of the air f of 1200 feet per second at l if) in the diffuser as will appear from the following discussion.

When air is flowing at a velocity greater than the velocity of sound it cannot be brought to a subsonic velocity by a simple expansion as in a diverging tube since at or above sonic speed, expansion of the tubes of flow leads to an increase of velocity. Only if a shock wave occurs which lower the Velocity below sonic by an increase in entropy can an expansion cause a reduction in velocity and an increase in pressure.

In the compressor described, at design conditions, the supersonic velocity is brought to a sonic value by the converging portion of the nozzle. A mild shock occurs near the beginning of the expansion lowering the velocity below the velocity of sound in the local fluid. The further expansion then gives a static pressure rise and a decrease of velocity. Since the shock occurs when the velocity is very close to the sonic value, little available energy is lost and the diiusion is accomplished eiiiciently provided the W does not separate from the walls.

It is desirable to precipitate the shock wave near the throat, that is near sonic value of the velocity and the slot action will do this but it should only be done if separation from the wall can be prevented. Hence as pointed out above the diffusion downstream from the throat must be carried out in a normal diffusion passage, that is in a passage which has the walls extending downstream from the throat substantial distances before being greatly curved or being abruptly expanded in passage cross sectional area. rhe passage walls should lap for a substantial distance upstream beyond any rapid change in direction of a portion of a blade. Abrupt change in direction of the walls Will cause separation of the flow from the diverging walls. Shock waves may also cause separation. Preferably the aft portion of a blade should lie substantially along the direction of the fore portion or at least the aft portion should lie more along the direction of the fore portion than along a line perpendicular to a plane tangent to the leading edges of the adjacent blades forming a rotor passage.

Separation of the boundary layer from the walls is caused by the steep adverse pressure gradient through the shock wave. The boundary layer flow is unable to proceed against the sharply rising pressure and actually ilows forward close to the wall, causing the main ow to separate from the wall.

In the present invention, the two devices are used to prevent separation. It will be noted in Figures 1 and 3 that the inner wall of the passage 5! is straight, all the curvature occurring along the outer wall. It is where the wall is curving from the flow that the separation will be apt to occur. It will not be as likely to occur at the inner wall which is straight. Separation at the curved wall will be prevented by the centrifugal pressure which tends to force the air against the outer wall.

It will also be noted that the outer or curved Wall of the passage 5I or shroud ring 51 has the holes 59 which bleed off the boundary layer air and prevent separation. There are a number o these holes spaced. peripherally about the shroud and for a short distance along the axis.

In Fig. lb and in Fig. 3a is shown the alternate diiuser which has the discharge slot 60 served with compressed air through a plurality of tubes 62 leading to the annular cavity 64 from the ration of the diiuser ilow from the wall... Thev form of construction shown in Fig. 1b and in Fig. 3a is an alternative fornito' that shown in Figs. l and 3. Only one form, either' that of Fig. 3 or Fig. 3a', is used at one time to theV exclusion of the other form.

The air leaves the passages 5 I of' rotor' 2 I with an absolute velocity of appreciable magnitude. Av goodly portion of this velocity energy is converted to static pressure energy as the air is further diilused in the stator passages 6l of Figure 2 formed by stator vanes 63 located in the diverging annular portion of case I-c. Figure 4 shows a radial section of the stator diffuser' passages (ilV taken along line 6 4 of Figure 2.

The final high pressure air leaves passages 6I, Figure l, to be collected in scroll passage, G5' of case io for continuous delivery to a reservoir or' machine for which the compressor is employed.

Windage loss in any centrifugalc'ompressor is nearly always one of the main causes for the low adiabatic efciency oi this type compressor. It is already a well-known fact that impellers having an outer shroud, such as shroudfl'l or" Figure l, are more eiiicient than those having no shroud and using a closely fitting housing. To obtain even better eihciency for impeller I'I in Figure l,

the annular labyrinth partitions le, which areY machined directly into the case Ia, are incorporated for two reasons. labyrinth seals to cut down on air blow-by from the compressor; and second, to reduce the windage circulation pockets as shown at l2.

Incorporated throughout the unit shown in Figure i is a special type low-friction oil seal wherever there might be a change for oil to pass unwanted. To show the principle of this seal y the forward impeller bearing I3` is considered. The principle is to provide an air annulus 8@ in termediate to the shielded ball-bearingv I3 and the labyrinth 32 such that when high pressure air is introduced in the air annulus 8h by means of tube Sli connected to the high-pressure annulus pocket B6, there will be enough air ilow toward the bearing I3, regardless oi the air leaking out the labyrinth seal 82, to satisfactorily prohibit oil particles from migrating toward andthrough the labyrinth. This same airthat is flowing toward the bearing I3, besides keeping the oil from passing the bearing, accomplishes the job oi scavenging oil slinger reservoir 29 after by-passing bearing I3 by means of passages 88 to the reservoir The high pressure caused thereby in reservoir 2s relative to atmospheric pressure pushes any oil and excess airv out through the oil scavenger tube d to be delivered by means or a return oil line from exit port 92 to a vented oil tank that would be part of the oil system installation.

Lubrication of bearings I3, I5, I9 and-planetary gears 23, 35 and 39 is accomplished by the normal practice of supplying cil under high pressure to inlet port IM from which it is distributed by means of suitable holes drilled in theelements of the machine including shaft l, planet gear mounting bolts 25, sleeve spacer 2l, and ballbearing spacer sleeve 96.

A similar sealing, scavenging and oil system is employed for bearing S2 as shown on Figure l.

A rotor having a nozzle passage for converting supersonic velocity to static pressure I will call a supersonic rotor.

First, to form. a set ofV In another form of the invention shown in Fig ure 6 compressed'y elastic luidis directed' to the supersonic rotor I' by the aXial-ilowrotor IZ". This carries about its periphery two stages of blading, namely, the rst stage composed of blades I ile' and the second stage composedv o1" blades IGS. Stator blades |08 and III) cooperate"` with the rotor blades to'd'irect compressed uid through the annular' passageY II'2-r. enters through. the'in-let II4" across which stream-- line struts IIS` extend to*l support the'outer case At the downstream end of passage H2 there'isI a stage of adjustable guide vanes IZilwhich direct the uid peripherally so that it has a large peripheral velocity upon approaching the supersonic nozzle 5I. This velocity is` also magnied by the contraction in passage IIZ forming the? exit nozzler Il which can raise the' issuing absoluteV velocity to sonic velocity or higher.- The to that already describedv with respectY to Figure 1.

The guide vanes Wilare placed in the large cross section oi passage |52 where the fluid vee locity is subsonic. This makes it possibleV for vanes i2@ to deect the flow Without producing compressibility turbulence.

The vanes are adjustedlby rotating ring |36' about the case. Each vaneris pivotally mounted by its shaft |32 and an articulated arml |34 con-t nects each shaft to the ring |30'.

It is a feature of this invention that the supersonic nozzle 5| is placed'at a greater radius than the axial flow rotor blades I 04 andV Ii. The latter must be operated well` below the velocity of sound while the supersonic nozzle should be operated at asY high a speed as: the material will permit. This difference in diameter permitsv both rotors (Idil and It?) to be mounted upon the same shaft. This greatly simplifies the drive since the high speed gears like 23 are eliminated.

The passage I i2 expands in cross section in the downstream direction, chiefly because the mean diameter of the annulus increases. The greater area reduces the velocity which in turn reduces the losses in the flow.

The design of Figure' 6 can be made to produce as great a pressure rise as that of Figure 1 as well as produce the structural advantage described, and also provides for a greater rangev of efcient delivery oi volume. This is so because the vanes |29 can be adjusted to direct the fluid at the proper angle into the supersonic nozzle `5I as the rate of rotation of the rotors changes. This is very important for machines such as turbines which must operate eiiiciently over a large variation in rotative speed.

Any of the passage structures conducting fluid are essentially nozzle structures. The rotator and stator nozzles or passages can be regarded as subpassages of the main flow passage.

In another form or" the invention Where size and cost are to be reduced, the stages of the axial compressor are placed close to the supersonic rotor. The rotors Ic and' |02a are the same as described for Figure 6 with respect to the blades and nozzles. The guide vane Idil is different being shown fixed in the nozzle I I5.

It may be observed particularly in Figure 1 that the exit area of the passagel is substan- The iluid` tially greater than the inlet area. This is an important feature since it ena-bles the rotor 2| where p is the mass density of the fluid in slugs per cu. ft., U is the peripheral velocity at the average radius of the ilow and u is the component of peripheral velocity added to the air by the rotor.

If the velocity in the direction of the axis of passage 5| were the same for inlet and exit (as they would be for a subsonc flow and equal inlet and exit areas) there would be no change in peripheral velocity, that is u would be zero since it is only the diierence in peripheral components of the velocity at inlet and exit along the axis of 5 When the inlet and exit areas are different the velocity vectors and hence their peripheral components are different.

It is also a feature oi this invention that the passages 5| diffuse the ilow radially instead of peripherally as in the conventional axial-now compressor where the curving of the blades or their mean camber line provides a larger area at exit from the passages than at the inlet of the passages between the blades.

The straight vanes 53 also present structural and cost advantages.

Tapering the passages in the radial direction has the added advantage that the opposite walls are substantially alike and disposed alike with respect to the resultant ilow vector at the entrance to the passages.

The advantage of having the flow directed toward the supersonic rotor against its direction of rotation may be observed from Figures 8 and 9.

Figure 8 shows the vector diagram for a case where the structure ahead of the supersonic rotor directs the ow axially toward the rotor along vector |50. When combined with the rotor peripheral vector |52 this gives the resultant vector |54 relative to the rotor 2|.

If the back pressure is reduced the axial flow through the compressor will increase for the same rate of rotation. This is the vector |50' may be multiplied by 3 for instance giving the new axial velocity vector |60 equal to 3 CM. The new relative resultant vector is |62. The change in angle of approach of the air relative to rotor 2| is AAar and is about 30 degrees which is a greater range of angles than the blades of the rotor can accommodate. They can accommodate only about 16 degrees.

In Figure 9 the nozzle structure ahead of the rotor 2| directs a flow of iluid toward this rotor along the vector |64 whose axial component is still CM. This vector combined with the peripheral vector |66 gives the relative vector |68. If the back pressure is decreased so that the new axial component is SC'M the vector |64 becomes |10. This combined with |66 which remains constant gives the new relative velocity |12. The change in direction of the air approaching the rotor is then naz which is about '7 degrees.

It is thus clear that by giving the flow from the structure ahead of the rotor a at angle with respect to the rotor with the velocity directed against the direction of rotation of the rotor 2| the range of angles which the rotor must accommodate is made very small, in the instance cited 7 which is well within the capabilities of even straight or at blades. This is important for subsonic flows and is very important for supersonic flows which are very sensitive to a flow oblique to the blades of the rotor.

The larger the angle B can be made the smaller is the range of angles Aa.

Where the ilow in the rotor 2| is diffused radially the rotor may also be called a radial diffusion rotor.

In a conventional axial flow rotor the amount of diffusion is the difference in the width between two streamlines approaching the nose of two adjacent blades and the width between two streamlines leaving the trailing edges of the same blades. Since the pressure rise is dependent on the diiiusion, the pressure rise varies with the angle of approach of the fluid to the blades. On the other hand the amount of diffusion in the radial diffusion rotor is built into the rotor by way of the ratio of exit to inlet area. Hence the radial diffusion rotor has a far more constant pressure rise for a wider range of fluid delivered per revolution. rThis is very important for an axial flow machine which has the disadvantage of a sharp drop in pressure with increasing mass ow per revolution.

A radial diffusion rotor gives its best eiiiciency when the passage inlet has a radial width which is small in comparison to the distance of the inlet from the axis of rotation. In other words if the blades are considered as clening the passages, the ratio oi the radius to the blade root to the radius at the blade tip should be large, of the order of 0.90. With such a ratio there is not a great difference in the head added to the air at the root and tip. With a small ratio there would be a large difference which would lead to losses in the diffusion following the rotor. Consequently it is important that a radial diffusion rotor be used following a number of stages which have compressed the air into an annulus of small radial width or large ratio of its two radii. For this reason the last stage of an axial flow lcompressor is the best place for a radial diiusion rotor.

To recapitulate, I employ supersonic nozzles distributed about the peripheral part of a compresser rotor to compress elastic fluids. The nozzle is adapted to convert a supersonic relative velocity of the fluid to static pressure. Since structurally there is a limit to the speed of rotation I arrange for oppositely rotating rotors, one delivering fluid to the other. Because of the, counterrotation the relative flow of velocity rel. ative to the one with supersonic nozzles can be well above the velocity of sound without dangerof structural failure.

As already remarked, in this invention, the throat to precipitate the shock wave is provided by the curvature in the outer wall of the flow passage of the rotor. The shock wave will extend inward from the outer wall transversely across the passage with the shock intensity a maximum at the outer wall. The pressure rise across the shock wave tends to cause the flow to separate from the diverging wall but this tendency is suppressed by the high centrifugal pressure arising from the rotation. (If even larger angles of diusion are desired the boundary layer is controlled by the openings 59 and 60.) Since static pressures operate in all directions the flow is also restrained from separating from the hub peripheral surface by the rise in static pressure from rotation at this locality. With the walls diverging radially the pressure rise from the shock wave is increased by the diffu- .sion assuring after the shock. `This is not feasiible .if 'the .diffusion `is in the .peripheral direction .since `to .provide the ,diffusion the blades must be `oludvedand the convex surface of the blade will .introduce an adverse pressure gradient readily y.causing ,separation from the convex wall. Because of lthis tendency to separate from the blade wall, supersonic compressors of the peripheral diffusion type vemploy a minimum of diirusion and rely for the pressure rise chiefly on 'the change in pressure across the shockwave and Qn little or no diffusion .downstream therefrom. JA .radial diffusion rotor provides a far higher pressurerise for the same eciency'by suppress- .ing .the tendency to ow VSeparation and by providing forlargerdiffusion after the shock Wave.

T11-.one form of the invention, the rst rotor V.or .-i-mpeller compresses by centrifugal Vforce.

ln another form of the invention, to eliminate .the `gearingwhich .may be troublesome lin small diameter compressors, I rotate all rotors in the rsa-me direction, To get a counterrotation of the flow entering the supersonic compressor, I em- F105! stator vanos which -deiiect the air periph- -ieral'ly in a :direction ,counter to the supersonic rotor.

"llo 'maintain eiiciency over a wide range of relative Vspeeds l employ adjustable vanes just vahead Aof the 4supersonic rotor. I place these -vanes v:preferably in a flow .of subsonic velocity. 'By adjusting the vanes the proper direction of approach can be given the iow about to enter thefsupersonic rotor.

Bownstream from the yad,instable vane I construct the passage-conducting the dow so as to give Va Ihigh velocity 4relative to the supersonic rotor.

'It .will now be clear that i have disclosed a :novel and e'iicient compressor of small dimensions, flight weight, and low cost, embodying the vseveral unique features originally specied as objects. "it is `to `be understood however that the invention not limited to the particular construction illustrated and described and that I intend .to claim it broadly as indicated by the scope ofthe appended claims.

lI claim:

1..:In combination in a compressor, a supersonic rotor mounted for rotation about an axis, said rotor having a plurality of diverging ,passages spacedfrom said axis and directed with a component of length along said axis, each said passage having anexit portion of increasing cross sectional rear in the downstream direction, a casing ahead of said motor adapted to llead a iiow of fluid up to the inlets of said passages,

axial-flowrotor having blades mounted therein, means mounting .said axial iiow rotor with its blades in said casing ahead of said supersonic rotor for rotation to compress the said flow of `L duid therein, rla `plurality of adjustable stator blades peripherall-y mounted in said vcasing between said rotors, means to adjust said stator blades to direct the fiow into vsaid supersonic rotor counter thereto, each said passage having `an exit of greater radial depth and cross sectional area than the inlet thereof adapting each said passage to convert supersonic velocity 'to static pressure-and means to rotate said rotors to corn-press fluid,` the portion of said Vcasing between-rotors having-an annular cross section of Aexpending area inthe downstream direction.

L'2. in combination in a compressor, v-a super- Usonic r.rotoramounten for rotation `about `Van axis,

said rotor having 'a plurality of `diverging passages spaced from said axis and ldirected with a ,component of lengt-h along said axis, each said passage `having an exit `portion of increasing cross sectional area in the downstream direction, a casing ahead of said rotor adapted to lead a VIiow of fluid up to the inlets of said passages, an axial-now rotor having blades mounted thereon, ,means mounting said axial flow rotor with its blades in said casing ahead of said supersonic rotor for rotationto compress the said l*low of fluid therein, a plurality of adjustable stator `blades periphera'lly mounted in said casing between said rotors, Ymeans to Vadjust said stator blades to direct Vthe iiow into said supersonic rotor, and means .to rotate said rotors to compress nuid, each said passage having an exit of greater radial depth and cross sectional area than Vthe inlet thereof adapting each lsaid passage to convert supersonic velocity to static pressure, the .portion of said casing between rotors having'an annular cross section of expanding area inthe downstream direction, the rst ,said rotor having a diameter' substantially greater than thetip diameter of the second said rotor to provide `for supersonic action of the first saidrotor.

3. .In combination in a compressor, a rotor, a 4counter-rotation supersonic `axial ow rotor, .means mounting said rotors for rotation about an peripherally adjacent radial walls in said supersonic rotor defining .passages therethrough, the lirst saidrotor being .adapted to dis- `Charseriuid into theinletof .said v.passages at a relative supersonic speed Vand with `a Component of velocity directed Yagainst the direction ofrotation of. said supersonic rotor, each .said oasbeing rotatable with said supersonic rotor and having an increasing cross sectional area and increasing radial depth in the downstream `direction :to convert the supersonic Velocity to t-'efpressure compressing said fluid, -each -said passage .having an rex-it facing rearward -to fdischarge Adindin the general direction of said axis, ,and means to apply power Vto .said supersonic :rotor .to rotatethe inlet of said passages -at said relative supersonic speed.

In combination in a `compressor adapted to deliver fluid against a substantial back pressure, a n lazie structure mounted therein having a plui of perifp-herally adjacent passages therethrough each comprising a converging inlet Aportion succeeded by a throat Vand a diverging exit portion of increasing cross sectional area and radial depth in the downstream direction, an inipeller rmounted ahead of said structure for rotation about an axis and adapted yto discharge a iiow of fluid into each said passage inlet portion with supersonic velocity relative to said iniet, each said passage being peripherally spaced inthe same plane transverse to said axisme ans to rotate vsaid impeller to providesaid ow, each said passage having a slot `in its wall nearer said throat than the exit of said passage, and means .to induce a ,iow through said slot .to localize near d throat a shock wave precipitated bysaid inpassage area and said back pressure.

5, in combina-tion in a compresor `having a main 4flow passage therein, an axial flow rotor 1subpassages having Vinlets and exits spaced 'si-rom said axis, each said exit facing rearward to direct said now rearward therefrom in the general direction of said axis, a fluid impeller mounted ahead of said rotor for rotation about said axis adapted to discharge elastic fluid into the inlets of said sub-passages, and means to rotate said rotor and impeller in opposite directions to provide a supersonic flow of elastic fluid relative to said inlets of said rotor, said main passage increasing in cross sectional area and radial depth between the inlets and exits of said subpassages adapting said rotor to convert the fluid supersonic velocity to static pressure.

6. In combination in a compressor, a supersonic rotor mounted for rotation about an axis, said rotor having a plurality of axially directed passages therethrough spaced from said axis and rotatable with said rotor, said rotor passages being peripherally adjacent, and each of said passages having a downstream portion thereof of increasing cross sectional area and radial depth in the downstream direction, a source of iluid under pressure, a duct adapted to conduct fluid to the inlets of said passages from said source of fluid, said duct having a converging nozzle at its exit to convert the fluid pressure to high fluid velocity, said nozzle including vanes set obliquely to said axis for directing said fluid into the inlets of said passages against their direction of rotation, and means to rotate said rotor at supersonic speed relative to iluid adjacent said inlets to compress and impel fluid through said passages.

7. In combination in a compressor adapted to impel fluid against a substantial back pressure, an axial flow rotor having a plurality of passages therethrough rotatable with said rotor and having inlets and exits spaced from the rotor axis, each said exit facing rearward to discharge uid rearward in the general direction of the axis of said rotor, means to rotate said rotor about said axis with a fluid supersonic velocity relative to the inlets cf said passages to induce flows through said passages, said passages each having peripheral walls divergng radially in the downstream direction so a fluid adjacent thereto flowing against said back pressure gives rise to a shock wave in each said passage tending to cause separation of said flow from said walls and tending to prevent conversion of dynamic pressure to static pressure, and means to induce a flow through a said wall to induce conversion of dynamic pressure of a supersonic fluid flow to static pressure within said passages, each said exit of a said passage being greater than the inlet thereof in radial depth and cross sectional area.

8. In combination in an axial ilow compressor adapted to pump a iluid against a substantial back pressure, a nozzle structure supported therein, said structure having a plurality of radial blades defining a plurality of passages therebetween each having an inlet and an exit, an impeller mounted ahead of said structure for rotation about an axis, said impeller having its discharge exits in communication with the inlets of said passages to direct a flow of iluid thereinto, means to rotate said impeller to provide a flow of elastic iluid through said impeller exits with supersonic velocity relative to said passage inlets, said blades being substantially straight along a substantial distance in the direction of the passage flow, said passages being bounded by opposed peripheral walls diverging in the downstream direction of the passage ilow to provide a diverging portion of cross sectional areas increasing in the downstream direction, each said passage having an entrance portion of delasing cross seevtional area and a throat portion preceding said diverging portion to reduce said supersonic velocity to sonic velocity, each said dverging portion serving in cooperation with said back pressure to precipitate a shock wave in the fluid flowing therein so that said diverging portion can convert the sonic velocity in said throat to static pressure, a wall of said passage having a slot therein near said throat, and means to induce a flow through said slot to precipitate said shock` wave near said throat.

9. In combination in an axial flow compressor adapted to pump a iluid against a substantial. back pressure, a nozzle structure supported'. therein, said structure having a plurality of radial blades defining a plurality of passages'- therebetween each having an inlet and an exit,r an impeller mounted ahead of said structure for' rotation about an axis, said impeller having its? discharge exits in communication with the inlets of said passages to direct a flow of iluid thereinto, means to rotate said impeller to provide a ilow of elastic fluid through said impeller exits with supersonic velocity relative to said passage inlets, said blades being substantially straight along a substantial distance in the direction of the passage flow, said passages being bounded by opposed peripheral walls diverging in the downstream direction of the passage flow to provide a diverging portion of cross sectional areas increasing in the downstream direction, each said passage having an entrance portion of decreasing cross sectional area and a throat portion preceding said diverging portion to reduce said supersonic velocity to sonic velocity, each said diverging portion serving in cooperation with said back pressure to precipitate a shock wave in the fluid ilowing therein so that said diverging portion can convert the sonic velocity in said throat to static pressure, a wall of said passage having a slot therein upstream from the passage exit, and means to induce a ilow through said slot to precipitate said shock wave a substantial distance upstream from said exit, opposed walls of said passage being substantially straight downstream beyond said slot for a substantial distance.

10. In combination to form a supersonic compresser, a case having an inlet and an exit, an impeller mounted in said case for rotation in one direction about a rotor axis to impel a flow of fluid through said case, a supersonic rotor mounted in said case aft of said impeller for rotation about said axis in counter direction to said impeller, said supersonic rotor having a plurality of blades spaced peripherally thereabout in the same plane transverse to said axis deilning a plurality of passages extending through from the front to the back of said rotor, said supersonic rotor blades making a substantial angle with respect to said axis of rotation, said impeller having a plurality of passages therethrough adapted to direct a fluid ilow into the inlets of said supersonic rotor passages, each said supersonic rotor passage having an inlet portion of decreasing cross sectional area succeeded by an exit portion of radially increasing cross sectional area, the inlet portion of each said supersonic rotor blade having a substantially straight length and the rear portion of each said blade being more nearly in line with the direction of said length than in line with the direction of said rotor axis to provide a form for each said supersonic rotor passage adapted to convert supersonic velocity to static pressure, and means to rotate said impeller in one direction and said supersonic rotor in the other direction at such speeds that the `supersonic rotor has a supersonic speed relative to the fluid flow directed toward its passage inlets.

11. In combination to pump a fluid against a substantial back pressure, a case, 4a nozzle structure mounted within said case, said structure having a plurality of blades serving as walls spaced apart peripherally along the wall of said case dening a plurality of passages extensive between the leading and trailing edges of said blades, each said passage comprising an inlet portion of decreasing cross sectional area and a throat and an exit portion of radially increasing cross sectional area in the downstream direction, an impeller mounted in said case ahead of said structure for rotation about an impeller axis and adapted to discharge a flow of fluid in the general axial direction into the inlet of each said passage with supersonic velocity relative to said inlet, the inlet portion of each said blade being substantially straight, means to rotate said impeller to provide said flow, said blade portion defining a said passage exit portion extending downstream substantially in line with the direction of said inlet portion of said blades for a substantial distance beyond said throat to provide a passage form suitable to convert said supersonic velocity to static pressure, each said passage exit portion serving in cooperation with said back pressure to precipitate a shock wave in the fluid flowing therein, a said wall of said passage having a slot therein substantially upstream from the trailing edges of said blades defining said passage exit, and means to induce a flow through said slot to control the location of said shock wave.

12. In combination in a compressor having a main flow passage with a portion thereof of decreasing cross sectional area in the downstream direction of a flow within, a plurality of stages of axial ilow rotor blades mounted in tandem in said main passage for rotation about an axis to impel a flow of uid through said stages in succession, said stages compressing said fluid through successively smaller annular cross sections of said main passage and a radial diffusion rotor mounted downstream from said stages for rotation about an axis, said diffusion rotor having a plurality of peripherally adjacent rotor passages in said main passage adapted to receive said fluid from said axial flow stages by way of said main annular passage portion of reduced cross sectional area, said diffusion rotor passage lying in the same peripheral plane transverse to said axis, each said diffusion rotor passage having radially diverging walls and an exit cross sectional area and radial depth greater than its inlet cross sectional area and radial depth, said inlets and exits being spaced by similar distances from said axis, said exits being directed rearward to direct a uid flow rearward in the general direction of said axis.

13. In combination in a compressor, a supersonic rotor mounted for rotation about an axis, said rotor having a plurality of radially diverging passages spaced from said axis, each said passage having an exit of greater area and radial depth than the inlet thereof, each said passage extending through from front to rear of said rotor to said exit facing rearward to direct uid rearward in the general direction of said axis, a casing ahead of said rotor adapted to lead a flow of fluid up to the inlets of said passages, an axial-flow rotor having blades mounted therein, means mounting said rotor with its blades in said casing ahead of said supersonic rotor for p rotation to compress the said flow of fluid therein, a plurality of adjustable stator blades peripherally mounted in said casing between said rotors, means to adjust said stator blades to direct the flow from said axial ilow rotor into said passages of said supersonic rotor counter thereto, and means to rotate said rotors to compress fluid, said means being adapted to give said supersonic rotor a supersonic speed at the inlet of said passages relative to the air approaching said supersonic rotor.

14. In combination in a compressor, an axial ow rotor having a plurality of peripherally adjacent rotor passages therethrough from front to rear of said rotor and spaced outward from the rotor axis, each said passage having its exit and inlet rotatable with said rotor and having said exit facing rearward to discharge a fluid flow in the general axial direction, means to rotate said rotor about said axis to induce a flow through said passages, each said rotor passage having a peripheral wall diverging radially with respect to said axis to increase the cross sectional areas in the downstream direction to provide an exit area of each said passage greater than the inlet area thereof, and means to induce a flow through said peripheral Wall between said inlet and exit of each said passage to suppress separation of the fluid from said wall.

15. In combination in a compressor, a rst rotor, a counter-rotating supersonic rotor, means mounting said rotors in tandem for rotation about an axis, said supersonic rotor having an axially directed passage extending therethrough from front to back thereof and rotatable therewith, said first rotor being adapted to supply fluid to the inlet of said passage with a supersonic velocity relative to said inlet, said passage being rotatable with said rotor and having an increasing cross sectional area and increasing radial depth in the downstream direction to convert the supersonic velocity to static pressure, and means to apply power to said supersonic rotor to rotate the inlet of said passage at said relative supersonic speed.

EDWARD A. STALKER.

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